Fenestration products include windows, doors, and various types of polygonal and rectangular framing in general. In the manufacture of fenestration products, wood and metal materials have been used, such materials being relatively rigid, hard and dense. The fabrication of corner joints made of two angularly disposed rails was not difficult and securement means therefor to provide a non-yielding relation between two angularly disposed rails was readily made because the fastening elements, such as nails, screws, etc., could be tightly secured and fixed to the material of the rails without loosening after being subjected to loads.
Present construction methods have sought lightweight heat insulator-type materials for use in fenestration in order to provide readily handled materials and to provide continuity of insulation characteristics throughout a building structure which may include insulated walls, insulating type double pane windows and material having insulating characteristics used for window and door frames. Such lightweight type materials include thermoplastic materials such as a high density cellular polyvinyl chloride which may be rapidly extruded in selected cross-sectional shapes for a selected design of a window or door. However, such thermoplastic materials are relatively soft and the degree of purchase of fastening elements such as screws and nails in such material was inadequate. Such fastening elements when tightened and subjected to loads became loose and further tightening of the fastening elements sometimes resulted in eroding of the thermoplastic material forming the hole receiving the fastening element. Sustained purchase in such soft materials of screws was not satisfactory for desired construction standards.
Prior proposed methods and constructions for joining two members at a right angle corner, for example, have including inserting an anchor plate transverse to the axis of one member and passing a securement nail or screw through the other member and into and through the anchor plate in a wood construction. See Hansen, U.S. Pat. No. 2,955,291. Another prior proposed corner joint for frame structures included the use of a threaded insert in one member and a threaded bolt for engagement therewith passing through the other member and into the first member to provide a rigid fixed corner joint. See Ottosson, U.S. Pat. No. 3,845,604. In the latter patent, the frame material was wood or extruded aluminum section. In the first mentioned patent, the material of the frame members included fiberboard, a relatively soft material which does not provide sustained purchase for fastening elements.
In U.S. Pat. No. 4,203,189, the problem of fastening a thermoplastic heel to a shoe was facilitated by heating a metal fastener to a temperature above the softening temperature of the plastic material and then driving the fastening element into the thermoplastic material of the heel.
In such prior proposed constructions, the concept of this invention of producing thermoplastic frame members for fenestration uses and providing a production method and system for preparation of stock material to the step of rapidly interconnecting angularly disposed elements of said frames was not suggested.